The percent of left ventricular wall (including ventricular septum) replaced by scar was determined in 70 necropsy patients with a healed transmural myocardial infarct (MI). The mean MI size in the 12 patients with and in the 44 without severe narrowing of the left main coronary artery was identical (each 13%). The percent of 5-mm segments with severe (cross-sectional area narrowing 76-100%) narrowing by atherosclerotic plaques in each patient ranged from 3-93% (mean 44) and did not correlate with MI size (r=-0.20).